Field of the Invention
The present disclosure relates to the field of infrared image sensors, and in particular to a method and device for performing offset and gain corrections in an image captured by an array of pixels sensitive to infrared light.
Description of the Related Art
In the field of infrared (IR) imaging, performing offset correction in captured images, without the use of a shutter or shutter-like hardware, presents a major challenge for uncooled IR imaging devices, such as microbolometers, and also for cooled IR imaging devices. Such imaging devices comprise an array of IR-sensitive detectors forming a pixel array.
Spatial non-uniformity between the pixels of the pixel array, which is responsible for the offset to be corrected in the image, varies not only in time but also as a function of temperature. This problematic is generally dealt with using an internal mechanical shutter in the imaging device, and involves periodically capturing an image while the shutter is closed in order to obtain a reference image of a relatively uniform scene that can then be used for calibration. However, there are several drawbacks of using a shutter, such as the additional weight and cost, and the fragility of this component. Furthermore, for certain applications, the use of a shutter is unacceptable due to the time that is lost while the shutter is closed and calibration takes place. During this calibration period, no image of the scene can be captured.
Image processing techniques for correcting offset have been proposed as an alternative to using a shutter. However, existing techniques are complex and/or do not adequately correct the image. There is thus a need in the art for an improved method of offset correction in an infrared image.